CVE-2026-73376: Ultimate Maps by Supsystic Auth Bypass

CVE-2026-73376 Overview

CVE-2026-73376 is an unauthenticated PHP Object Injection vulnerability affecting the Ultimate Maps by Supsystic WordPress plugin in versions prior to 1.5.0. The flaw stems from insecure deserialization of untrusted input [CWE-502], allowing remote attackers to inject crafted PHP objects without authentication. Successful exploitation can trigger unsafe magic methods within the WordPress runtime, leading to remote code execution, data tampering, or full site compromise. The vulnerability is reachable over the network with low attack complexity and requires no user interaction.

Critical Impact
Unauthenticated attackers can inject serialized PHP objects to achieve remote code execution and full compromise of vulnerable WordPress sites running Ultimate Maps by Supsystic below version 1.5.0.

Affected Products

Ultimate Maps by Supsystic WordPress plugin versions prior to 1.5.0
WordPress installations with the vulnerable plugin activated
Sites exposing plugin endpoints that accept serialized user input

Discovery Timeline

2026-08-18 - CVE-2026-73376 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-73376

Vulnerability Analysis

The vulnerability originates from insecure deserialization of attacker-controlled data within Ultimate Maps by Supsystic. When the plugin passes untrusted input to PHP's unserialize() function, an attacker can construct a serialized payload that instantiates arbitrary PHP objects. During deserialization, PHP invokes magic methods such as __wakeup, __destruct, or __toString on the reconstructed objects.

Attackers chain these methods across classes loaded in the WordPress runtime to form a POP (Property-Oriented Programming) gadget chain. Depending on available gadgets in WordPress core, other plugins, or themes, this chain can escalate to arbitrary file writes, SQL injection, or remote code execution. The Patchstack advisory confirms the flaw is exploitable without authentication.

Root Cause

The root cause is improper input validation before deserialization [CWE-502]. The plugin deserializes data received from an untrusted source without verifying its structure, type, or origin. No integrity check, allowlist, or safe alternative such as json_decode() is applied prior to reconstruction.

Attack Vector

Exploitation occurs over the network against exposed plugin endpoints. An attacker submits a crafted serialized PHP payload to a vulnerable parameter, and the plugin passes it to unserialize(). Because no authentication is required, any remote client that can reach the WordPress site can attempt the attack. Refer to the Patchstack Vulnerability Report for technical specifics.

Detection Methods for CVE-2026-73376

Indicators of Compromise

Requests to Ultimate Maps by Supsystic endpoints containing serialized PHP markers such as O:, a:, or s: in parameter values
Unexpected PHP error logs referencing unserialize(), __wakeup, or __destruct during plugin requests
New or modified PHP files under wp-content/uploads/ or plugin directories following suspicious POST traffic
Outbound connections from the web server process to attacker-controlled infrastructure shortly after plugin requests

Detection Strategies

Inspect HTTP request bodies and query strings for serialized PHP object signatures targeting plugin AJAX or REST routes
Correlate web server access logs with PHP error logs to surface deserialization failures tied to plugin URIs
Alert on WordPress file integrity changes affecting plugin, theme, or upload directories after external requests

Monitoring Recommendations

Enable WordPress audit logging to capture plugin option changes, user creation, and file modifications
Forward web server, PHP-FPM, and WordPress logs to a centralized platform for retention and correlation
Deploy a Web Application Firewall (WAF) rule set that flags serialized payloads in requests to plugin endpoints

How to Mitigate CVE-2026-73376

Immediate Actions Required

Upgrade Ultimate Maps by Supsystic to version 1.5.0 or later on all affected WordPress sites
Audit sites for signs of compromise, including unauthorized administrator accounts, modified plugin files, and unexpected scheduled tasks
Rotate WordPress administrator passwords, secret keys in wp-config.php, and any credentials stored in the database if compromise is suspected

Patch Information

The vendor addressed the vulnerability in Ultimate Maps by Supsystic version 1.5.0. Site administrators should update through the WordPress plugin dashboard or by replacing plugin files with the patched release. See the Patchstack Vulnerability Report for advisory details.

Workarounds

Deactivate and remove the plugin until the update to 1.5.0 or later is applied
Restrict access to plugin endpoints using WAF rules that block serialized PHP payload patterns
Limit administrative access to WordPress with IP allowlists and multi-factor authentication to reduce blast radius

bash

# Update the vulnerable plugin using WP-CLI
wp plugin update ultimate-maps-by-supsystic --version=1.5.0
wp plugin list --name=ultimate-maps-by-supsystic --fields=name,version,status